1. Field of the Invention
The present invention relates to an ultraviolet laser beam and, more in particular, a method of and an apparatus for providing a high powered ultraviolet laser beam. The invention can be used in a number of industrial applications from the book industry to the production of printed cards and in the medical treatments as well.
2. Description of the related art including information disclosed under 37 CFR .sctn..sctn.12.97-1.99.
It is known that lasers commercially available in the wavelength range lower than 300 nm are essentially of four types:
(a) excimer lasers with powers up to a hundred of watts but at very low repetition frequency (up to some hundreds of Hz); PA1 (b) dye lasers which can be operated both in continuous wave mode and in pulsed mode (some Hz), powers of some hundreds of milliwatts being provided in the first case, and some in the second case; PA1 (c) gas lasers operating only in continuous wave mode and with very low powers of the order of one hundred of milliwatts; PA1 (d) solid state lasers with doubling of frequency operating at high repetition frequency with powers lower than one watt. PA1 (1) the efficiency of the infrared-green conversion to be enhanced as a result of the phase addition of the green generated in the first doubling crystal to the green previously generated and propagating in the cavity;